/Engine/Source/Runtime/Core/Public/Templates/SharedPointer.h
IMPORTANT: This has different behavior toGetSharedReferenceCount()== 1 in a multithreaded context. The expectation is that this will be used when a user wants exclusive write-access to an otherwise-immutable object. Care still needs to be taken when pinning TWeakPtrs to make new shared references.
True if there is only one shared reference to the object, and this is it!
bool IsUnique() const